The Center for Mass Spectrometry at The Scripps Research Institute is seeking funds for the purchase of an electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) time-of-flight (TOF) mass spectrometer for high accuracy MS and tandem mass spectrometry experiments. The existing MALDI FTMS instrument was purchased by Scripps seven years ago and has performed over 25,000 analyses and is used by over 800 researchers. The Center is in critical need of this high accuracy ESI and APCI capability for its NIH funded researchers. The existing MALDI FTMS is one of the first designs and has very limited sensitivity and versatility with respect to analyzing different types of compounds. In addition, the MALDI FTMS reliability is poor as signal variability from day to day is high and the vacuum system has been rebuilt twice in the last two years. The Center received NIH funding in 1993 for a SCIEX API-3 ESI triple quadrupole mass spectrometer, which is still being used for routine ESI-MS and ESI-MS/MS analyses. However this and all other instrumentation at Scripps does not offer the high accuracy that the ESI/APCI TOF-reflectron would offer. The ESI/APCI TOF reflectron would facilitate the analysis of natural products, metabolites, carbohydrates, peptides, proteins, oligonucleotides and a host of synthetic organic compounds required by the researchers listed and other laboratories throughout the institute. The research of seven faculty (listed below) would greatly benefit from ESI/APCI TOF reflectron capabilities. Six of these researchers have established NIH funding, the seventh investigator, Philip Baran, has just begun at Scripps. These groups, alone, include over 200 postdoctoral associates and graduate students, a table of eight minor users (all NIH funded) is also provided. As with all the equipment within the Center, the use of the ESI/APCI TOF reflectron would also extend beyond this user group to the entire institute. [unreadable] [unreadable]